Investigation of critical heat fluxes in vertical tubes internally cooled by Freon-12, Part II - the development of a critical heat flux correlation for uniformly heated tubes

Abstract

Based on the parameter groups derived from a dimensional analysis a correlation for predicting critical heat fluxes (CHF) in a uniformly heated tube cooled internally by Freon-12 has been developed by systematically examining experimental data to establish the interrelationship of these dimensionless groups. Although the basic correlation agrees with much experimental data it is inaccurate for short tubes or low mass fluxes. To compensate for these effects corrective terms were introduced to provide a more generalised form. The correlation has been tested against approximately 2000 experimental data. It was found that apart from data at low exit qualities (less than 0.1) or short boiling lengths less than approximately 50 the correlation agrees with the data to within +- 10 per cent for boiling length ratios less than approximately 150; for values greater than 150 more than 90 per cent of points agree with the correlation to within +- 5 per cent.